fix missing comma in documentation output example

docs/sources/http_api/user.md

@@ -156,7 +156,7 @@ HTTP/1.1 200
 Content-Type: application/json
 
 {
-  "email": "user@mygraf.com"
+  "email": "user@mygraf.com",
   "name": "admin",
   "login": "admin",
   "theme": "light",
@@ -409,4 +409,4 @@ HTTP/1.1 200
 Content-Type: application/json
 
 {"message":"Dashboard unstarred"}
-```
+```